For what it sounds like you're talking about (I am in the same situation) you could create snippets with custom triggers.
For example, I found I had to often enter a private string variable in Action script often, so:
<snippet>
<content><![CDATA[
private var ${1}:${2:String} =
]]></content>
<!-- Optional: Set a tabTrigger to define how to trigger the snippet -->
<tabTrigger>pvar</tabTrigger>
<!-- Optional: Set a scope to limit where the snippet will trigger -->
<scope>source.actionscript</scope>
</snippet>
So, I can type "pvar" and tab.
However, in my post I was specifically referring to auto-completes (the menu that appears on ctrl-space), if there's only 1 or two adds I want to make.